Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds genuine behavior beyond that: each value names its original publisher (US Census, World Bank, Eurostat, CDC) and lists how alternate sources differ, plus the default-to-latest behavior — useful output-shape context not present in the annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two dense sentences with the primary action front-loaded and the mode enumeration immediately after; nothing is padded. The trailing Count_Person / country/USA example largely duplicates the schema's examples block, so it earns its place only marginally.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a read-only open-world lookup whose annotations already carry the safety profile and whose schema has full description coverage, the description is nearly sufficient: it covers the retrieval modes, default, publisher attribution and multi-source comparison. It stops short of explicitly routing agents to the find_* sibling tools, which is the only real gap.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the schema already documents all five parameters, including date mode syntax and the limit default/max. The description only echoes the "latest value (default)" behavior for the date parameter and adds no syntax or format detail beyond the schema — the baseline 3 for schema-does-the-work.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb ("Get the value") and a precisely scoped resource ("one Google Data Commons statistical variable for one place"), and enumerates the three retrieval modes (latest / dated / full series). An agent can tell this is a value-lookup tool, distinct from the datacommons_find_place and datacommons_find_variable resolvers, without opening the schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description explains the three retrieval modes and flags latest as the default, which implies when each mode applies. However, it never names an alternative tool or a when-not-to-use condition (e.g., "use datacommons_find_variable first if you don't know the variable dcid"), so routing guidance is only implied.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.